Of Power-cuts and Timing Demands

It is summer-time. That time of the year when power is most in need but yet, is cut. In the winter, when no one would mind (or will they?), there is no demand and hence, no cuts. Anyway, the point of inquiry is whether there is a universally good time for a power-cut. Answer: No…
The other most obvious question if one thinks about is is why cant we have power-cuts in winter, store that energy and balance the demand in the summer?
Answer: That is because there are no large-scale systems that can store energy. That is right. We have sub-1-inch laptops and pocket projectors and what not, but no good technology to store energy to use as needed and this is an unsolved problem since, say, the last 150 years or so. Where are the scientists? Where are the breakthroughs?